Prior art algorithms used an edge detection algorithm in the spatial domain to identify discontinuities in the image data and measure the change in intensity taking place over a number of pixels. It is difficult to set the threshold to detect bright pixels which may contribute to an edge due to the noise in the image. It is also difficult to set a region of interest and the criteria to calculate the defect density; susceptible to false detection due to lens roll off or edge effect.
U.S. patent application Ser. No. 11/180,816, filed Jul. 13, 2005, entitled “The Use Of Frequency Transforms In The Analysis Of Image Sensors”, by Greg L. Archer, et al. uses a single linear regression algorithm in the frequency domain to identify a linear pattern in the center of the image.
Although the currently known and used methods for detecting and removing streaks is satisfactory, improvements are always desirable. The present invention provides such an improvement.